Two kinds of ordered ZnO/TiO2 heterostructures were fabricated via a facile approach. The architecture of the TiO2 substrate could be controlled by alternating the filling forms of the template, and the morphology of the secondary ZnO nanostructure could be further tuned by adjusting the parameters of the hydrothermal reaction. Then two different morphologies of ZnO/TiO2 heteroarchitectures with ZnO nanorods and nanoplates growing on TiO2 shells and bowls were successfully achieved, respectively.
A novel method, thermo-catalytic decomposition of formaldehyde, is used to synthesize mesoporous ZnO crystals with enhanced photocatalytic activities. The mechanism of the mesoporous formation is investigated by synthesizing a series of samples at various systems and characterizing them with FT-IR, EDS, XRD, SEM, and TEM. The results show that formaldehyde can be adsorbed on the crystal planes of ZnO during the crystal growth and can then be catalytically decomposed into CO, CO2 and H2 during a sintering process. Because of the formation and the escape of these gases, which act as templates, the crystalline particles of ZnO are forced to rearrange consistently, and pores are formed in the internal crystal. Also, porous TiO2 crystals have been obtained via the same approach. Photocatalytic tests indicate that a porous ZnO crystal has higher activity than that of a nonporous one.
The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mame.201800681.
ZnS Quantum DotsHerein, a concise and novel method is developed to directly generate Mndoped ZnS QDs/alginate nanocomposite beads. In this method, the ionic gelation of alginate is employed to produce alginate gel beads in a solution of Zn 2+ and Mn 2+ ions. Subsequently, the gel beads serve as the reaction support for in situ synthesis of Mn-doped ZnS QDs in the beads through the reaction of sodium sulfide with Zn 2+ and Mn 2+ ions. The method has many benefits such as the simple preparation, the environmentally friendly process, the mild conditions, and the easy post-treatment for the beads. The resulting QDs/alginate beads are homogeneous and stable gel spheres which show clear fluorescence. TEM images demonstrate that Mn-doped ZnS QDs are homogeneously distributed within the QDs/alginate nanocomposite, and their average size is 2.4 ± 0.3 nm. Potentially, the QDs/alginate beads can be utilized for fluorescence bioimaging, as well as fluorescence detection toward metal ions.
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